1. Field of the Invention
The present invention relates generally to an apparatus and method for measuring the strength of the noises in a wireless communication system, and in particular, to an apparatus and method for measuring the strength of the noises in a reception apparatus of a wireless communication system supporting Orthogonal Frequency Division Multiplexing (OFDM).
2. Description of the Related Art
Generally, a transmission signal in the wireless environment, rather than in the wire environment, may suffer from considerable distortion due to various factors such as multipath, attenuation, time-varying noise, interference, etc. A fading phenomenon due to the multipath is closely related to the reflection on geographical structures or the movement of users, and a transmission signal that has experienced a fading channel is received at a reception apparatus after it is considerably distorted. This causes degradation of the entire system performance.
The fading phenomenon is the biggest obstacle to supporting high-speed data communication in the wireless environment. Therefore, to realize the high-speed data communication in the wireless environment, there is a need to minimize the loss in the wireless channel, such as fading and inter-user interference.
In the reception apparatus of the existing wireless communication system, various schemes are provided to measure the strength of the noises caused by the wireless channel, and remove the noises. In addition, the measured strength of the noises is used in such techniques as channel estimation, encoding and decoding, which are applied to the wireless communication system.
Therefore, for performance improvement of the techniques using the measured strength of the noises in the wireless communication system, there is a demand for a scheme capable of accurately measuring the strength of the noises from a received signal.
The reception apparatus of the existing wireless communication system performs an operation of estimating a channel gain from a received signal, and extracting a transmitted signal from the received signal considering the estimated channel gain. Therefore, the reception apparatus of the existing wireless communication system estimates noise components by removing the estimated channel gain and the transmitted signal to be extracted, from the received signal.
However, the noise component estimation method achieved in the reception apparatus of the existing wireless communication system may not accomplish accurate noise measurement not only due to an error occurring in estimation of the channel gain but also due to a low reliability of the extracted transmitted signal.